There are three ways that you can allocate stock when using the From Stock fulfilment method:
Allocate on order entry.
You can allocate stock during order entry provided you have selected Allocate stock on order entry on the SOP settings Order Processing tab. You may need to manually allocate stock using Amend Allocations if there was not enough stock to allocate fully on order entry.
Automatic Allocation.
Automatic allocation allocates stock to an order entry according to priorities you specify
Allocate manually.
If you choose to allocate stock manually, e.g. to reserve stock for preferred customers, then use Amend Allocations. Allocations per item are listed and can be increased or reduced as required.
When allocating stock, the system monitors stock levels at the warehouse specified for the item, and compares these to the quantities you allocate. Quantities allocated at the appropriate locations are updated. If Keep Movement History is selected on your stock product group settings Details tab, then the allocations are added to this history. Allocated quantities on order lines are also updated automatically.
If you are using the From supplier direct to customer fulfilment method, no allocations are performed. This is due to the assumption that the stock will be delivered directly to the customer. If you are using the From supplier via stock (back-to-back) fulfilment method, no allocations are performed until the goods are received in the Purchase Order Processing module.
What do you want to do?
Reference
Order processing (SOP settings)